Add/remove xml tags using a bash script

Using xmlstarlet:

#xmlstarlet ed -d "/a/b" file.xml > tmp.xml
xmlstarlet ed -d "//b" file.xml > tmp.xml
mv tmp.xml file.xml

This would not be difficult to do in sed, as sed also works on ranges.

Try this (assuming xml is in a file named foo.xml):

sed -i '/<b>/,/<\/b>/d' foo.xml

-i will write the change into the original file (use -i.bak to keep a backup copy of the original)

This sed command will perform an action d (delete) on all of the lines specified by the range

# all of the lines between a line that matches <b>
# and the next line that matches <\/b>, inclusive
/<b>/,/<\/b>/

So, in plain English, this command will delete all of the lines between and including the line with <b> and the line with </b>

If you'd rather comment out the lines, try one of these:

# block comment
sed -i 's/<b>/<!-- <b>/; s/<\/b>/<\/b> -->/' foo.xml

# comment out every line in the range
sed -i '/<b>/,/<\/b>/s/.*/<!-- & -->/' foo.xml

You can use an XSLT such as this that is a modified identity transform. It copies all of the content by default, and has an empty template for b that does nothing(effectively deleting from output):

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

<!--Identity transform copies all items by default -->
<xsl:template match="@* | node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
</xsl:template>

<!--Empty template to match on b elements and prevent it from being copied to output -->
<xsl:template match="b"/>

</xsl:stylesheet>

Create a bash script that executes the transform using Java and the Xalan commandline utility like this:

java org.apache.xalan.xslt.Process -IN foo.xml -XSL foo.xsl -OUT foo.out

The result is this:

<?xml version="1.0" encoding="UTF-16"?><a><c><cc>
      Something
    </cc></c><d>
    bla
  </d></a>

---

EDIT: if you would prefer to have the b commented out, to make it easier to put back, then use this stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

    <!--Identity transform copies all items by default -->
    <xsl:template match="@* | node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>

    <!--Match on b element, wrap in a comment and construct text representing XML structure by applying templates in "comment" mode -->
    <xsl:template match="b">
        <xsl:comment>
            <xsl:apply-templates select="self::*" mode="comment" />
        </xsl:comment>
    </xsl:template>

    <xsl:template match="*" mode="comment">
        <xsl:value-of select="'&lt;'"/>
            <xsl:value-of select="name()"/>
        <xsl:value-of select="'&gt;'"/>
            <xsl:apply-templates select="@*|node()" mode="comment" />
        <xsl:value-of select="'&lt;/'"/>
            <xsl:value-of select="name()"/>
        <xsl:value-of select="'&gt;'"/>
    </xsl:template>

    <xsl:template match="text()" mode="comment">
        <xsl:value-of select="."/>
    </xsl:template>

    <xsl:template match="@*" mode="comment">
        <xsl:value-of select="name()"/>
        <xsl:text>="</xsl:text>
        <xsl:value-of select="."/>
        <xsl:text>" </xsl:text>
    </xsl:template>

</xsl:stylesheet>

It produces this output:

<?xml version="1.0" encoding="UTF-16"?><a><!--<b><bb><yyy>
            Bla
        </yyy></bb></b>--><c><cc>
      Something
    </cc></c><d>
    bla
  </d></a>